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Single circuit to dual circuit
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Todd
Posted 2020-08-02 10:22 AM (#601590)
Subject: Single circuit to dual circuit



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hi folks.
My current single circuit master brake cylinder has a 1/4 "line to the front tee. All other lines have only 3/16". Now I would like to convert to a dual circuit brake system. Does one line from the Dual master cylinder have to be thicker here too, or can both lines coming out of the dual circuit master cylinder also have 3/16 "?
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58coupe
Posted 2020-08-02 11:28 AM (#601593 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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The reason the front line is 1/4" is because you are feeding 4 wheel cylinders, 2 on each wheel. The rear is only 1 wheel cylinder on each side. What are you changing, just the master cylinder?
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Todd
Posted 2020-08-02 1:17 PM (#601599 - in reply to #601593)
Subject: Re: Single circuit to dual circuit



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Hi. Thanks for reply. I want to change the master brake cylinder (single to dual) and all brake lines.
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Powerflite
Posted 2020-08-02 8:26 PM (#601616 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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I use a special 1/4 type (forgot the thread size) of tube nut on a 3/16 line at the top and block off the rear port.
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71charger_fan
Posted 2020-08-02 9:53 PM (#601621 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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You can get a 25' coil of copper nickel brake line with an assortment of fittings off of Ebay for less than $30. I wound up buying the Eastwood on car flaring tool and was very pleased with how well it worked.
https://www.eastwood.com/eastwood-on-car-flaring-tool-for-3-16-tubin...

http://www.forwardlook.net/forums/forums/thread-view.asp?tid=63722&...

Edited by 71charger_fan 2020-08-02 10:15 PM
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51coronet
Posted 2020-08-04 8:59 AM (#601678 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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Best flaring tool I have used so far is ridgid
https://www.amazon.com/RIDGID-83037-Precision-Ratcheting-Flaring/dp/...

It is nearly automatic, makes perfect flares each time, can do stainless line easily, not very expensive considering how well it works. You cant lose either piece with how its permanently attached to each other which is weird for me since I have used the dual piece ones for 20+ years. It just works well. Very nice tool. It moves in an orbital motion which flares line very nice. Old ones just pressed into the hole and relied on the tool to hold it without the tube slipping downward. Moving in a small orbit is the proper way to flare lines.
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Todd
Posted 2020-09-08 12:23 PM (#603021 - in reply to #601678)
Subject: Re: Single circuit to dual circuit



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This is the bendix style master cylinder i want to use for the conversion:

[img]https://thumbs.picr.de/39393590af.jpg[/img]

I'm unsure with the ports. The right/first port on that picture is 1/2"-20 INV as primary and the left/second port on the pic is 9/16"-20 INV as secondary.
The smaller Primary port (right on pic) feeds the two front lines (goes into the tee) and the bigger secondary (left on pic) feeds the line to reward, am i right?

And...do i have to use a 1/4" line from primary port to the FL tee? (as it actually is at my single cirq. master)
And all other lines 3/16?

Edited by Todd 2020-09-08 12:30 PM
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Powerflite
Posted 2020-09-08 12:45 PM (#603024 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes, that is correct that the front port of the master feeds the rear brakes. Chrysler ported them backwards for some reason.
Also, read my post above. I don't use a 1/4" line. Use a 3/16" line with a special tube nut that fits the larger port. The thread size is 7/16-24 like these on ebay.

https://www.ebay.com/itm/7-16-24-Inverted-Flare-3-16-Tube-Zinc-Nut-B...

Also, make sure you get the correct 9/16-20 Chrysler tube nut. GM uses a more common 9/16-18 tube nut that won't work.

Edited by Powerflite 2020-09-08 12:47 PM
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Todd
Posted 2020-09-08 1:15 PM (#603026 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Great support, thanks a lot!! This is good to know. Thank you very much for the infos
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Todd
Posted 2020-09-09 1:03 PM (#603057 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Does anyone know if the push rod of the single master will fit to the dual bendix ?

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Powerflite
Posted 2020-09-09 2:29 PM (#603058 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes, it fits. It's a tighter fit, but it works. The original push rod to the newer master has a rubber keeper on it. It won't work with that keeper, so I leave it out.

Edited by Powerflite 2020-09-09 2:47 PM
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LD3 Greg
Posted 2020-09-10 12:07 AM (#603068 - in reply to #601678)
Subject: Re: Single circuit to dual circuit


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51coronet - 2020-08-04 8:59 AM

Best flaring tool I have used so far is ridgid
https://www.amazon.com/RIDGID-83037-Precision-Ratcheting-Flaring/dp/...

It is nearly automatic, makes perfect flares each time, can do stainless line easily, not very expensive considering how well it works. You cant lose either piece with how its permanently attached to each other which is weird for me since I have used the dual piece ones for 20+ years. It just works well. Very nice tool. It moves in an orbital motion which flares line very nice. Old ones just pressed into the hole and relied on the tool to hold it without the tube slipping downward. Moving in a small orbit is the proper way to flare lines.


But, does it do double flares? I don’t see the double flare anvils in the pic.

Greg
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1960fury
Posted 2020-09-10 7:35 AM (#603071 - in reply to #603068)
Subject: Re: Single circuit to dual circuit



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LD3 Greg - 2020-09-10 12:07 AM

51coronet - 2020-08-04 8:59 AM

Best flaring tool I have used so far is ridgid
https://www.amazon.com/RIDGID-83037-Precision-Ratcheting-Flaring/dp/...

It is nearly automatic, makes perfect flares each time, can do stainless line easily, not very expensive considering how well it works. You cant lose either piece with how its permanently attached to each other which is weird for me since I have used the dual piece ones for 20+ years. It just works well. Very nice tool. It moves in an orbital motion which flares line very nice. Old ones just pressed into the hole and relied on the tool to hold it without the tube slipping downward. Moving in a small orbit is the proper way to flare lines.


But, does it do double flares? I don’t see the double flare anvils in the pic.

Greg


Search for Ridgid 459 on Ebay.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l131...

It is not really a wear part, so used should be ok. Got mine for under 10 Dollars, like new, back when you could ship parts from the US to Europe. Excellent tool for the money. It does SAE 45° double flares, but you need the little adapters but they are cheap and easy to find.

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hemidenis
Posted 2020-09-10 7:25 PM (#603087 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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a thread like this one is the real reason for the creation of this website....helping other fellow members... Great job to everyone.
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Todd
Posted 2020-09-12 4:20 AM (#603119 - in reply to #603087)
Subject: Re: Single circuit to dual circuit



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I totally agree. Thanks to everyone here!!
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Todd
Posted 2020-11-18 2:01 PM (#605743 - in reply to #603119)
Subject: Re: Single circuit to dual circuit



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Hi Guys. I have to go back to this with a question.
I installed the master cylinder and all the special connections recommended to me in this thread fit very well. For the normal lines (from brake cylinders/hoses to the tee) I have
bought only 3/8-24 fittings in the short version - pls. see link (TN01 -left on the picture)

https://www.ebay.de/itm/Standard-SAE-Inverted-Flare-Brake-Line-Fitti...

The old lines sometimes had the same short 3/8-24 fittings on one side but longer 3/8-24 fittings on the other side. The longer ones mostly went into the wheel brake cylinders.

Can I use only the short fittings for all ends of the lines instead? Any concerns?
I've already tried this and they fit very well when i tighten it. I think they're not too short....why did they use the longer fittings?!

Edited by Todd 2020-11-18 2:07 PM
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Powerflite
Posted 2020-11-18 2:23 PM (#605744 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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The longer fittings aren't required as the thread length on the female side is the same. I'm not sure what the purpose for using the longer length was, except maybe it makes it easier to install & make sure it is straight. But anyway, you don't have to use long fittings. You can re-use the original fittings if they are in good shape, if you like.
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Todd
Posted 2020-11-18 3:40 PM (#605748 - in reply to #605744)
Subject: Re: Single circuit to dual circuit



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I got it. So i will go on working at the linings. Thanks a lot again for your support.
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1960fury
Posted 2020-11-18 4:12 PM (#605750 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes, the longer thread isn't required and all of the original cars I ever owned never had the long thread at the wheel cylinders but I think on the distribution block, on the line coming from the MC with a reinforcement sleeve on the brake line (1/4"). I theory it makes sense since it prevents, or reduces movement of the brake line at the secton of the brake line that is most likely to crack, the transition from flare to straight, covered by the fitting. Keep in mind, there is always some movement between the frame and the body.
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samstrader
Posted 2020-11-19 2:34 AM (#605769 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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On my 1955 Plymouth, a brake hose was used to connect the master cylinder to the distribution manifold. Do people usually keep using a hose or do they replace the hose with steel brake line? The distance between the master cylinder and the distribution manifold is far enough apart that there is plenty of room for flex of a brake line I think. I'm asking this because of Sid's comment regarding movement between the frame and the body.
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Powerflite
Posted 2020-11-19 2:44 AM (#605771 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Steel line with a loop. The loop will provide some flex movement to prevent the line from cracking.
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samstrader
Posted 2020-11-19 2:53 AM (#605773 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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Thanks Nathan, I like a steel line better than a hose and there is plenty of room for loop or several turns in the line that will provide flex.
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1960fury
Posted 2020-11-19 7:30 AM (#605777 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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On 60/61s the distribution block is mounted on a flexible bracket and the main line from the MC is reinforced at the ends, or at least the lower end, so there is no loop required.
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Todd
Posted 2020-11-19 12:03 PM (#605789 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Okay, the hint with movement between frame and body is very good. Please look at the pictures. This is my first job with self-made brake lines. So please don't be so strict. Can I leave it like that, or do I have to have a loop in front of the master brake cylinder?

[img]https://thumbs.picr.de/39900288fm.jpg[/img]

[img]https://thumbs.picr.de/39900287dz.jpg[/img]

[img]https://thumbs.picr.de/39900286ph.jpg[/img]

[img]https://thumbs.picr.de/39900285my.jpg[/img]




Edited by Todd 2020-11-19 12:06 PM
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samstrader
Posted 2020-11-22 8:18 PM (#605941 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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I think this is an absolutely beautiful job and I also think you have plenty of flex. The lines have more than one turn which gives flex and they are long horizontal legs that also help with flex. Additionally, the distribution manifold is mounted on a bracket that also gives a little flex.

It looks like the brake line from the front port on the master cylinder might be touching the emergency brake cable. If it is, it would be better if the brake line didn't touch anything so that there is no chance of rubbing a hole in the brake line with vibrations.

You did a beautiful job and now your car is much safer since you have a much improved brake system.
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Todd
Posted 2020-11-23 4:12 AM (#605948 - in reply to #605941)
Subject: Re: Single circuit to dual circuit



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Wow thanks a lot for the compliment
I will check the line and the emergency cable.
I have to say that I enjoy flaring more than bending lines

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Todd
Posted 2020-11-28 2:00 PM (#606130 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Folks, I can't get the brakes bleed. The new dual-circuit master has experienced extensive benchbleeding. Installed and on all nipples, BF arrives. Bubble free! Have already depleted 1.5 liters. But ZERO pressure on the pedal. I'm still going crazy here. The brake circuits are separated ... even on the two rear wheels, after a bubble-free venting, there was zero pedal pressure. Then also done at the front and zero pedal pressure. That's impossible.
Benchbleeding was successful, no bubbles.

I have now ordered a new one (60's mopar Bendix style maste cylinder). Can you think of anything else .... did I miss something ....? The new pipes are tight, nothing is dripping anywhere

Edited by Todd 2020-11-28 2:01 PM
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wizard
Posted 2020-11-28 3:54 PM (#606132 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Manual brakes or power brakes?
Wrong pedal ratio?
Brake shoes adjusted correctly?
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1960fury
Posted 2020-11-28 5:09 PM (#606134 - in reply to #606132)
Subject: Re: Single circuit to dual circuit



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wizard - 2020-11-28 3:54 PM

Manual brakes or power brakes?
Wrong pedal ratio?
Brake shoes adjusted correctly?


Manual brakes.

Always try to pin the problem down. Have you plugged the MC at the ports for testing? Continue that way until you find the problem.
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56D500boy
Posted 2020-11-28 9:49 PM (#606141 - in reply to #606130)
Subject: Re: Single circuit to dual circuit



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Todd: You might want to review "Dels56"'s thread on "Spongy Brakes". He had similar problems with his new dual circuit MC:

http://www.forwardlook.net/forums/forums/thread-view.asp?tid=74238&...



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Todd
Posted 2020-11-29 4:01 AM (#606147 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Thanks for reply folks. Manual brakes, pedal ratio perfect, shoes lightly grinding, all ok. Plugged the ports only on the bench. Worked, has had pressure when stroking.
My old single master has 1.125" bore, the bendix has 1" bore. Can this be the reason?
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wizard
Posted 2020-11-29 4:50 AM (#606148 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes of Course, the displacement must be the same Todd, Most probably You should have pressure if You pump the brakes fast. The supplied volume of brake fluid must be the same as the oem mc.
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Todd
Posted 2020-11-29 6:10 AM (#606150 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Okay the new master must have the same bore size. In this case i need a drum/drum master with 1.125 " bore. Hard to find, i did not found one yet....Does anyone have any advice?
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wizard
Posted 2020-11-29 6:52 AM (#606151 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes Todd, but mind that the stroke must deliver the same volume as well. Divide by six, the front cylinders must have 4 of this volume and the rear cylinders must have 2.

So, practically, mount the oem cylinder in a wise, fill up and pump a couple of strokes. Measure a full stroke volume.
Do the same with the new cylinder and check the volume for each port. If the new cylinder supplies the same volume for both ports, then it will never work without a adjustable brake reduction valve for the rear circuit.

Even with this valve, you will have a low pedal with the lesser diameter of the m/c

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Todd
Posted 2020-11-29 9:44 AM (#606154 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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That sounds logical and understandable. But how am I supposed to do it. I can't buy some masters and then measure whether it fits. There are also no volume specifications for new masters. If you are lucky, the size of the bore is indicated, nothing more. Here on the board, many people have surely already converted from this single master, which is probably the same for almost everyone, to a dual master. It should still be possible to find out which dual master is suitable for the conversion, in the case of drums around....
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wizard
Posted 2020-11-29 10:20 AM (#606155 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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I've been on the forum for some years now, but I still havn't seen one thread about sucessfully installed dual circuit m/c, drum/drum or disc/drum or for that matter disc/disc. In fact, I remember mostly problems about this.

That said, I don't think the braking power of only the rear drums would be much better than the emergency brake if the front circuit should fail. If the rear circuit would fail, the braking force will be far better than the emergency brakes though.

Hypothetically, if a dual circuit m/c gives the same volume in both ports, it would be possibly to hook up a diagonal system, left front and right rear, right front and left rear. Perhaps the pulling forces would be too steep anyway.

A thing came to my mind Todd, does the new m/c has a residual valve for both circuits?
If not, that might be the core of the problem, since residual valves are used to maintain constant pressure on the brake system.

For drum brakes, a 10 lb. residual valve is used to hold pressure against the springs in the drum. This allows the drum brake to engage more quickly and reduces pedal travel.

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wizard
Posted 2020-11-29 10:28 AM (#606156 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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See also this old one from the cellars http://www.forwardlook.net/forums/forums/thread-view.asp?tid=52082&...


And these ones https://www.summitracing.com/int/search/part-type/residual-pressure-...
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Powerflite
Posted 2020-11-29 11:42 AM (#606159 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Sven, the only reason you don't see successful installs is because we don't post about them. Also people with problems don't usually post when they solve the problem. But I assure you that there are many hundreds of successful dual circuit master installs. I have done at least seven of them and haven't had any issues. If he truly has zero brakes, then there is a faulty part that is either leaking, has trapped air in it, or not holding pressure. A small bore master will travel much longer than you would generally like, but it would at least create pressure at the end of its stroke. So he needs to start investigating where the problem lies. The only time I encountered an issue similar to this, I eventually found that I had a bad rear hose that was seeping. I found this because when I plugged the rear line, everything worked as it should. He needs to plug the master off one by one and see where the problem lies as Sid suggested.

Edit: I have also encountered a time when I purchased a new master that was bad right out of the box.

Edited by Powerflite 2020-11-29 11:46 AM
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56D500boy
Posted 2020-11-29 12:37 PM (#606161 - in reply to #606159)
Subject: Re: Single circuit to dual circuit



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Powerflite - 2020-11-29 8:42 AM
Edit: I have also encountered a time when I purchased a new master that was bad right out of the box.


This is exactly why I posted the link to Dels56 "Spongy Brakes" thread. That is what Del found out: Bad master right out of the box.

(And here's me with a new Chinese Raybestos dual master that I have had for a couple of years and not installed yet. Oh boy.)



Edited by 56D500boy 2020-11-29 12:38 PM
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wizard
Posted 2020-11-29 12:40 PM (#606162 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Thanks' Nathan, then I kindly ask our members that have sucessfully installed a dual circuit master cylinder with drum/drum system to post the m/c they installed and the diameter of the bore.

It must be frustrating for the ones wanting to do this modification to "invent the wheel" all the time.

We could then try to collect this info in one thread for future use.

Yes, I'm aware that new m/c's sometimes comes with damaged parts and/or wrongly mounted parts as well.
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Todd
Posted 2020-11-29 12:44 PM (#606163 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Thanks all. The dual has built in residual valves. I pulled the primary piston but everything looks fine. I'll reassemble it and then do the pressure test when it's installed. Plug one port at a time and depress the pedal ....
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Todd
Posted 2020-11-29 12:47 PM (#606164 - in reply to #606162)
Subject: Re: Single circuit to dual circuit



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wizard - 2020-11-29 12:40 PM

Thanks' Nathan, then I kindly ask our members that have sucessfully installed a dual circuit master cylinder with drum/drum system to post the m/c they installed and the diameter of the bore.

It must be frustrating for the ones wanting to do this modification to "invent the wheel" all the time.

We could then try to collect this info in one thread for future use.

Yes, I'm aware that new m/c's sometimes comes with damaged parts and/or wrongly mounted parts as well.


Yes that is a great idea !!
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1960fury
Posted 2020-11-29 1:40 PM (#606165 - in reply to #606155)
Subject: Re: Single circuit to dual circuit



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wizard - 2020-11-29 10:20 AM

I've been on the forum for some years now, but I still havn't seen one thread about sucessfully installed dual circuit m/c, drum/drum or disc/drum or for that matter disc/disc. In fact, I remember mostly problems about this.




Than you forgot about mine. I changed from stock to Wilwood disc/disc with dual Wilwood MC in 98 or 99 and it went without any problems.
Didn't even bench bleed (because I didn't know about that).
I installed a residual valve years later becaue after prolonged driving w/o braking the first brake application the pedal travel increased and delayed braking.

Most people run into problems because they forget DRUMS always need a residual valve and most aftermarker dual MC's don't have them built in,
like the OE MC.
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wizard
Posted 2020-11-29 2:40 PM (#606167 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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No Sid, I didn't forget that you made a sucessfull installation - you chose state of art parts that were ment to be working together. A professional set-up for sure.

Many here perhaps does not want to go "all-in" in a project, so they're looking for a more economic solution.

As you wrote, drums really must have residual valves with the proper pressure value (10 lbs), not just "any" residual valves.

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Powerflite
Posted 2020-11-29 2:47 PM (#606168 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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I would agree, except that the 1 1/8" OEM master doesn't actually have a residual valve in it, at least for '56-'58. I know this because I am running disc brakes with the original master and there is no drag on them at all like there would be if there was a residual valve in place. I suspect that things changed once the drum brake design changed, but not sure when a residual valve started to be used in them.

Edited by Powerflite 2020-11-29 2:48 PM
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1960fury
Posted 2020-11-29 3:51 PM (#606171 - in reply to #606168)
Subject: Re: Single circuit to dual circuit



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Powerflite - 2020-11-29 2:47 PM

I would agree, except that the 1 1/8" OEM master doesn't actually have a residual valve in it, at least for '56-'58.


That would really surprise me. Not rarely the old residual valves are not working properly and therefore could work with discs, that require @ 2lbs pre-pressure, IIRC.
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1960fury
Posted 2020-11-29 3:57 PM (#606172 - in reply to #606168)
Subject: Re: Single circuit to dual circuit



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Powerflite - 2020-11-29 2:47 PM

I would agree, except that the 1 1/8" OEM master doesn't actually have a residual valve in it, at least for '56-'58.


This 39-58 Mopar kit shows a valve:

https://www.ebay.com/itm/Dodge-Plymouth-Truck-cars-1939-1958-New-Mas...
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Powerflite
Posted 2020-11-29 4:00 PM (#606173 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yeah, maybe the valve was bad on them, but I've tested it on 4 vehicles, and they were all the same.
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1960fury
Posted 2020-12-01 9:29 AM (#606210 - in reply to #606171)
Subject: Re: Single circuit to dual circuit



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1960fury - 2020-11-29 3:51 PM

Powerflite - 2020-11-29 2:47 PM

I would agree, except that the 1 1/8" OEM master doesn't actually have a residual valve in it, at least for '56-'58.


That would really surprise me. Not rarely the old residual valves are not working properly and therefore could work with discs, that require @ 2lbs pre-pressure, IIRC.


Did some research and of course pre-59 master cylinders had residual valves too. All drum systems need some pre-pressure in the lines.

Edited by 1960fury 2020-12-01 10:30 AM
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Todd
Posted 2020-12-01 11:27 AM (#606212 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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In the meantime, I've tested a lot. The new master has pressure on every outlet. So it's not defective.
After bleeding, however, as before, there is no brake pressure on the pedal. When the pedal is fully depressed to the floor, the rear brakes are gently braked.
But the pedal travel is far too long.
Then I installed and bleeded the old single circuit master. I have normal, full brake pressure on the pedal.
So it can only be due to the smaller 1 "brake piston of the new master. The piston is too small. But there is no drum / drum dual master with a 1,125" bore. There are many dual masters for disc / drum.
What do I do now? I stick with the one-circuit system. The lines and fittings are all new and therefore safe. At some point I'll maybe convert the front to disc. But not just yet.
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